Field of the Invention
This invention relates to the field of wheel suspensions, and particularly to wheel suspension systems that independently support the wheels of a vehicle in which a wide and low cargo floor is desired. This invention is an improvement to the wheel suspension systems described in my earlier patents, namely, U.S. Pat. No. 4,878,691, issued on Nov. 7, 1989, U.S. Pat. No. 4,934,733, issued on Jun. 19, 1990, U.S. Pat. No. 5,016,912, issued on May 21, 1991, and U.S. Pat. No. 5,275,430, issued on Jan. 4, 1994, all incorporated herein by reference.
For a variety of reasons, it is frequently desirable to have the cargo floor of a trailer, van, or similar vehicle as low as reasonably possible. A low floor provides for more efficient transportation of cargo, giving a vehicle more useable, internal space for given exterior dimensions. Also, a low floor placed close to the road surface makes for easier access to the vehicle. These and other advantages of a low cargo floor have motivated various proposals for low vehicle floors.
In U.S. Pat. No. 4,032,167, there is disclosed a trailer for transporting motorcycles. This trailer includes wheels mounted to fixed spindles that are bolted to a rigid frame. Because of this rigid attachment, considerable forces are imparted to the frame. Further, rigidly fixed wheels will have undesirable effects on the handling and ride comfort of a vehicle.
In another type of suspension system, the vehicle is supported on a through axle that extends the width of the vehicle below the vehicle frame. Examples of this are found in U.S. Pat. Nos. 4,580,798 and 4,615,539. Because the axle extends the entire width of the vehicle, the cargo space of the vehicle must be adapted to fit over the axle. Thus, the axle and the diameter of the wheel establish the height of the cargo floor above the ground.
In a different type of wheel suspension system, the through axle extending the width of the vehicle is replaced with short, independent axles present only at the sides of the vehicle. An example of this is shown in U.S. Pat. No. 4,666,181. This short independent axle is attached to a support arm, which is pivotably attached to the vehicle frame. With this type of suspension, the axle and wheel diameter no longer create a minimum height for the vehicle cargo floor. Other considerations, such as ground clearance, establish the height of the cargo floor. The suspension system components reside in or around the wheel well. This area around the wheel well, however, still represents limitations to the cargo area. Further compaction of the wheel suspension system will result in more efficient and convenient use of cargo space.
Briefly describing one aspect of the present invention there is provided an apparatus comprising a wheel, a wheel support, and an air spring. The wheel support is pivotally attached to the vehicle frame and is pivotable between a first position and a second position. The wheel support rotatably supports the wheel by the rotational axis. The wheel support includes an air spring support. The air spring urges the wheel support apart from the vehicle frame. The wheel support receives the air spring in the air spring support. The air spring support is located below the rotational axis. The wheel support may be of the trailing-arm type, in which the rotational axis is rearward of the pivot axis, or the leading-arm type, in which the rotational axis is forward of the pivot axis.
Briefly describing another aspect of the present invention, a wheel support is coupled to the frame by a pivotal attachment which permits adjustment of the camber angle of the wheel. Another aspect of the present invention concerns a wheel support that is pivotally coupled to a frame such that the pivotal attachment permits adjustment of the toe-in angle of the wheel. In another aspect of the present invention, a wheel support is pivotally attached to a cross-member of a frame, the cross-member being lower than the rotational axis of the wheel. In another aspect of the present invention, a wheel support is coupled to a transfer structure by first and second pivotal attachments that are located forward of the rotational axis. A spring is coupled to the wheel support below the rotational axis, and is also coupled to the transfer structure. Yet another aspect of the present invention includes a wheel support with a pivot axis located below the rotational axis. An air spring positioned between the frame and the wheel support is operably coupled to a source of compressed air. Another aspect of the present invention includes a wheel support pivotally attached to a frame, and a shock absorber for dampening motion of the wheel support, the shock absorber being located substantially below the rotational axis of the wheel. In yet another aspect of the present invention, there is a vehicle with multiple wheels for supporting the vehicle from the ground. The wheels are arranged on either side of the vehicle, such that the rotational axes of the wheels are not coincident.
These and other aspects of the present invention will be apparent from the following description of the preferred embodiment, the drawings, and the claims.